Refrigeration apparatus including liquid injection desuperheater



Aug. 24, 1965 R. M. SHRADER 3,201,950

REFRIGERATION APPARATUS INCLUDING LIQUID INJECTION DESUPERHEATER Filed Sept. 26, 1965 3 PIKE/V51? INVENTOR [gnaw/71 Jirader BY 2% m ATTORNEYS United States Patent M 3,201,950 REFRIGERATION APPARATUS INCLUDING LIQUID INJECTION DESUPERHEATER Raymond M. Shrader, Decatur, Ga., assignor to Lat-kin Coils, Inc., Atlanta, 6a., a corporation of Georgia Filed Sept. 26, 1963, Ser, No. 311,743 6 Claims. (Cl. 62.ll9'7) This invention relates to refrigerating systems, and ,more' particularly to improvements in the arrangements .for automatic capacity control of such systems.

It is well known that automatic capacity control of a -refrigerationsystem canbeobtained by the expedient of ally-passing ,a certain amount of the gaseous refrigerant discharged from the compressor around the condenser and evaporator andintroducingthe same; directly into the compressor suction line. There is a limit to the amount of :gaseous refrigerant which can be thus by-passed for the purpose of reducing system capacity, because of the super- ;heatingwhich may occur as the gaseous refrigerant again passes through the compressor. -If the gaseous refrigerant iscontinuously by-passed to the compressor-for long periods of time along such a short path wherein little heat iswithdrawn, it is obvious that the temperature of the --gaseous refrigerant will progressively rise due -to super- .heatingcf the gas upon each cycle of passage through the compressor, accompanied by transmission of heat to the compressor. This condition will tend to damage the compressor overa period of operation. A popular methrod of preventing the by-passed gaseous refrigerant from at- .tainingan excessively hightemperature which would ef- :fect overheating of the compressor during periods when .small evaporator load and by-passing of large amounts of gaseous refrigerant produce conditions exceeding the normalcapacity reduction limit,-has been to inject liquid refrigerant into the suction line vapor whereby the boil- .ing refrigerant in heat exchange relation with the suction gas .cools the suction; gas before it enters the compressor.

;By injecting liquid refrigerant into the suction gas in the suction'line, a serious practical difficulty is encountered particularly in smaller horsepower systems. With fluctuations in loads and stopping and starting the compressor ,with the associated starting of the vapor flow, quite: often theinjected liquid refrigerant will not properly vaporize in'the suction line gas and consequently the liquid passes into the compressor as a slug of liquid. It is easilyseen that the non-vaporized slug of liquid, being incompressible, is apt to break the piston or other parts .of the compressor.

An object of this invention-is the. provision of a novel refrigeration system having automatic capacity control "by-passe'dgas by injectingliquid refrigerant into heat exchange relationwith the by-passed gas to desuperheat the gas in order-that the temperature of the compressor will be maintained below levels where damage may result.

'Another object of this invention is the provision of a 3,2l,95 Eatented Aug. 24, 1965 not to be taken in a limiting sense, the scope of the invention being defined in the appended claims.

In thedrawings: FIGURE 1 is a diagram of a refrigerative/circuit utilizing the vaporizing chamber of the present invention.

FIGURE 2 is a view of a first embodiment of the vaporizing chamber partially in section and partially in elevation.

FIGURE 3 is a view of a second embodiment of the vaporizing chamber partially in section and partially in elevation.

Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, the refrigeration system of FIGURE 1 comprises a compressor it), of any suitable size and design, which discharges the refrigerant through line 11 to a condenser 12, herein illustrated as a conventional water cooled condenser. The compressed vapor phase refrigerant entering the condenser condenses to liquid .phase and is discharged through line 13 into a receiver 14 where the liquid refrigerant is stored. The liquid refrigerant is conveyed from the receiver 14 through conduit 15 to an evaporator 16.

The evaporator 16 may be of conventional construction, and is, of course, designed to have a selectedcooling capacity for the normal heat loads expected to be encountered. Conventional means is provided for metering flow of liquid refrigerant from the receiver to the evaporator through liquid line 18 in accordance with the heat load on the evaporator, as for example a thermostatic expansion valve 1'7, regulated by the usual control bulb 19.

To provide for automatic capacity control of the refrigeration system as the means to reduce the cooling capacity of the evaporator for low heat loads, instead of cycling the compressor on and off, a part of the hot gaseous refrigerant discharged from the compressor is bypassed around the condenser-receiver-evaporator legs of the refrigerant circuit through by-pass conduit 21. This by-pass arrangement serves both to deprive the evaporator of some liquid refrigerant, thus reducing its cooling capacity, and further prevents attainment of harmful conditions which would otherwise occur if the compressor were operated continuously and the liquid refrigerant inflow to the evaporator were throttled down to an appropriate value for low heat loads. With minimum heat load conditions at the evaporator 16, continued operation of the compressor It would reduce the pressure in the suction line 2%) to such a low value that problems of compressor shaft sealing, bearing lubrication and other prob- ,lems with which those skilled in the art are familiar would be encountered. With a by-pass line Zlconnected between the discharge line 11 and the suction line 20 around the condenser, receiver and evaporator whena low load condition is established at the evaporator 16'and the flow of vapor therefrorrihas been severelyrrestricted,

a controlled flow of gaseousrefrigerant into the suction. line 2%) may be established by bleeding a'portion of gase p have been found 'to'operate in a practical manner with a various refrigeration system capacities areas follows:

ous refrigerant from discharge line 11.

The amount of vapor'allowed to enter the by-passline a, a 21 is controlled-by a conventional downstream pressure sensitive control valve 22 located in the by-pass line" 21.

"sorption o heat from the gaseous refrigerant with a s consequent change of state, of the resulting mixture to When the suction pressure in line 29 drops below a preelected value, this low pressure will activate the control valve 22, allowing the valve to open and permi'tting a recirculation .of gaseous refrigerant from the "discharge and expansion valve 17.

With a restricted flow a of liquid refrigerant tof'thev evaporator '16 to meet a low load condition,and are:

all, vapor while still within theconfines of tube 2'].

Representative sizes of the vaporizing chamber 26 that System: Number of Diameter Length Diameter Length 7 Capacity, 1 $64 Die. 'of Inner ofInuer: of Outer I of Outer Tons 'Orifice Tube 30 Tube 30 Tube 27 Tube 27 Holes 32 (in.) (in.)' (in.) (in.)

4 3 5 8 5 a 8 l 7 q 10 JO 1% 7' ll 10 16' 10 1% 13 24 V 13 i 1% v 18 '36 i 20 1% p 24 3 Indescribingthe:operation of the present'refrigeration a system, "and in particular the vaporizing chamber, it will 20 be assumed that the system is initially operatingunder' a condition of maximumlload. When the-evaporatorf16 sultant pressure decrease in suction line 20, it will'be" evident that the control valve 22 will remain open and a continue to recirculatethe vapor through the bypass line 21-and the compressorrltil 1 This continued recirculation of gaseous refrigerant through the compressor will produce v a cumulative heating effect at the compressor as 'the-iprogressively higher temperature gas is further superheated 'duringcompression, and if not offset, Twill produce a" temperature Withinthe compressor 1t? that has a danger.- ously high value; To offset :this'heating effect; asecond;

by-pass line 23 is connected from'liquid refrigerant line a '18 to by-passline 21,: through which-a portion of the a liquid refrigerant in line 13 may be injected into the hot I recirculating gaseous refrigerant in by-pa'ss line '21 to effect cooling of the by-passing refrigerant. To control the-fl'owof liquidrefrigerant.frorn'the condenser 12 to the evaporator 16.--With less vapor being'discharged I {is operating under-a maximum load, the liqui'cl'r'efrigerant [is fed through valve1 7to the, evaporatorat a maximum rate andis completely vaporized-and returned to the compiessorithr-Ough thesuction line; Thus, upon leaving the "evaporator the now vaporized refrigerant produces a certain temperaturerat the location of the bulb 19 this load conditionon the evaporator. Under highload-the compressor normally experiences no problems due toflow pressure or excessive superhea't as the't'e'mperfatur; does not'exceed that for which the system is designed when under full load-1 But when the evaporator is subjected to} a smallload, 01 no load conditions, a lesser temperatur'e is sensed by the. thermosensitivehbulb 19 and Vactivatesfthenvalve 17' to'restric't reflecting from the evaporator 16, ,the compressor 10, which is opti-on line 20. Thebulb 25 will sense the temperature of 1 line 20 and will modulate valve24 in such'relationas to provide a rate of refrigerant injection into! by-pass line '21 by way of a-vaporizing chamber26 such that thefrea 'frigerant willbe completely vaporized before'actual discharge into the by-pass line 21, thereby preventing a slug of liquid from reaching the @compressor. I

The vaporizing chamber 26, as shown in one preferred crating/continuously, begins to reduce the pressure in the suction line'20Q This reductionin' suction linegpress'ure willbe reflected through by-pass line 21: to; the automatic pressure responsive control valve 22 which will then open to permit a recirculation of'gaseous refrigerants from the discharge line 11 into the suction line 20. to

embodiment by FIGURE 2 comprises an outer elongated cylindrical tube 27 having a vapor inlet tube 28 on one end thereof and a vapor outlet tube 29 on the other end. 7 concentrically located within the outer-tube 27- is an.

innerelon'gated cylindrical tube 3t) coaxially arranged relative to the outer tube 27 'To provide access to inner tube 30 is, an inlet pipe 31rwhich extends outwardly at right angles from one end of inner tube 30 through an aperturein outer tube 27 toallowthe inlet pipe 31 to be connected to liquid injection lin 23. Inner tube- 30.

reduce the liquid refrigerant supply to the condenser and evaporator and increase the suction-line pressure at the intake of'the compressor upto a normal value.

"I As has been noted above, continued recirculation of the discharge; gaseous refrigerant,through.the compressor will permit adange'rously high temperature "to be imparted to the'gaseous refrigerant. 'Once this temperature reaches a predetermined value,'the thermo-sensitive bulb -25 r'esponds" and allows the'thermo-expansion valve into the hot gaseous lre frig'eranfwhich' flows through tube, 27 and surroundsfinner tube 30.

frigerant admitted through'valve 24 into tube 38 and the by-passing gaseous refrigerant in tube 27, produces boilpressure of the liquid line 23, the boiling refrigerant with- It will thus be seen that heat exchange between the inj-ectedliquid It? 24, located in liquid by-pas's line 23, to open and admit liquid refrigerant tothe vaporizing'chamber' 26'. When thisrcon di-tion occursthe liquid refrigerant flows into the innertube 30 by pipe 31where it boilsdue 'to the heat exchangeywith' the gas tflowing within the loutertube 27. As stated, above, the boiling refrigerantis discharged throughjorifice holes 32; in line mist-like particles which absorb heat from the gaseous refrigerant flowing through outertube 2f7fso that a complete vaporization occurs within the confines of outertube 27, and in the manner contemplated by the inventiongthe gas leaving. tube 27 by way ofvapor outlet tube 29 contains no slugs of liquid that could possibly be transmitted to the compressor'lfl.

1 A second embodiment of this invention as shown in FlGURE- i comprises an elongated cylindrical outer tube Z'i'lhavirig'locatd, concentrically therein an elongated cylindrical tube 30 with orifice,holes"32.,. Thei'construction of this embodiment is just, the o ppositeas thatshown in tube 30 is discharged through orifices 32 in a spray of;

.fine mist-like particles of liquid refrigerant which are:en-'

trained with'the gaseous refrigerant and present a c om bined surface area sufficiently large to allow rapid abin FIGURE 2, "that is, the liquid refrigerant is admitted through line 31' into the outer tube 27' and the liquid I thenboils by heatiexchange with thehotgaseous re- .frigerant flowing through the inner tube, 30 with the result that the boiling liquid will then be injected in a fine spray into the inner tube 30' through orifices 32'. In all other respects this embodiment operates in the same manner as that shown in FIGURE 2.

In the refrigerant system of the present invention a high degree of modulation is achieved upon the temperature of the vapor entering the compressor 10, because thermo-sensitive bulbs 19 and 25 work in conjunction with one another. While the bulb 19 senses only the temperature of the discharged gas from evaporator 16 and controls it accordingly, bulb 25 senses the temperature of the return vapor at a point in the return line after the thermal effects of the gas from by-pass line 21 are introduced and is able to control the temperature conditions at the compressor by opening and closing valve 24 to admit into the vaporizing chamber 26 a flow of liquid refrigerant just sufficient in quantity to offset the undesirable heating effects of the by-passed refrigerant.

Those skilled in the art will recognize that the various structural elements of the system including the compressor, condenser, evaporator, connecting lines and control valves may be of any conventional nature and may be varied according to good engineering practice.

Various modifications may be made in the invention without departing from the spirit and scope thereof, and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and set forth by the appended claims.

I claim:

1. In a refrigeration system having automatic capacity control means for varying the capacity thereof including a compressor, condenser, receiver and evaporator having the usual hot gas line from the outlet side of the compressor to the condenser, a suction line from the inlet side of the compressor to the evaporator and a liquid line from the receiver to the evaporator, a hot gas bypass conduit directly connecting the outlet and inlet sides of said compressor, a liquid by-pass conduit directly connecting said receiver and said gas by-pass conduit, and means for regulating the flow of gaseous refrigerant through said gas by-pass conduit responsive to conditions in the system indicative of the load on the evaporator and pressure in the suction line; the improvement comprising liquid injection means in said gas by-pass conduit at the junction of said liquid by-pass conduit comprising a plurality of concentric tubular members, one of said tubular members having fixed sized orifices in heat exchange relation with the hot gas in said gas by-pass conduit wherein said orifices are so calibrated as to bring the liquid to a boil before said liquid is injected into said gas by-pass conduit whereby the injected liquid absorbs heat from the hot gas to effect complete vaporization of said injected liquid to prevent a slug of liquid from reaching said compressor.

2. In a refrigeration system having automatic capacity control means for varying the capacity thereof including a compressor, condenser, receiver and evaporator having the usual hot gas line from the outlet side of the compressor to the condenser, a suction line from the inlet side of the compressor to the evaporator and a liquid line from the receiver to the evaporator, a hot gas bypass conduit directly connecting the outlet and inlet sides of said compressor, a liquid by-pass conduit directly connecting said receiver and said gas by-pass conduit, and means for regulating the flow of gaseous refrigerant through said gas by-pass conduit responsive to conditions in the system indicative of the load on the evaporator and pressure in the suction line; the improvement comprising liquid injection means in said gas by-pass conduit at the junction of said liquid by-pass conduit comprising a pair of concentric tubular members, one of said tubular members mounted in said gas by-pass conduit to permit the hot gas to pass therethrough, the other of said tubular members having means to admit liquid from said liquid by-pass conduit, fixed sized orifices in the inner of said concentric tubular members spiralled therearound in heat exchange relation with the hot gas in said gas by-pass conduit wherein said orifices are so calibrated as to bring the liquid to a boil before said liquid is injected into said gas by-pass conduit whereby the injected liquid absorbs heat from the hot gas to effect complete vaporization of said injected liquid to prevent a slug of liquid from reaching said compressor.

3. In a refrigeration system having automatic capacity control means for varying the capacity thereof including a compressor, condenser, receiver and evaporator having the usual hot gas line from the outlet side of the compressor to the condenser, a suction line from the inlet side of the compressor to the evaporator and a liquid line from the receiver to the evaporator, a hot gas bypass conduit directly connecting the outlet and inlet sides of said compressor, a pressure sensitive valve in said conduit adapted to be actuated in response to a preselected pressure value in said suction line to admit hot gaseous refrigerant to said gas by-pass conduit, a liquid by-pass conduit directly connecting said receiver and said gas bypass conduit, a temperature sensitive valve in said liquid by-pass conduit adapted to be actuated in response to a predetermined temperature of the gas in said suction line to modulate the rate of liquid flow to said gas bypass conduit, the improvement comprising liquid injection means in said gas by-pa'ss conduit at the junction of said liquid by-pass conduit comprising a pair of concentric tubular members, one of said tubular members mounted in said hot gas by-pass conduit to permit the hot gas to pass therethrough, the other of said tubular members having means to admit liquid from said liquid by-pass conduit, fixed sized orifices in the inner of said concentric tubular members spiralled therearound in heat exchange relation with the hot gas in said gas by-pass conduit wherein said orifices are so calibrated as to bring the liquid to a boil before said liquid is spray injected into said gas by-pass conduit whereby the spray injected liquid absorbs heat from the hot gas to effect complete vaporization of said spray injected liquid to prevent a slug of liquid from reaching said compressor.

4. In a refrigeration system having automatic capacity control means for varying the capacity thereof including a compressor, condenser, receiver and evaporator having the usual hot gas line from the outlet side of the compressor to the condenser, a suction line from the inlet side of the compressor to the evaporator and a liquid line from the receiver to the evaporator, a hot gas by-pass conduit directly connecting the outlet and inlet sides of said compressor, a liquid by-pass conduit directly connecting said receiver and said gas by-pass conduit, and means for regulating the flow of gaseous refrigerant through said gas by-pass conduit responsive to conditions in the system indicative of the load on the evaporator and pressure in the suction line; the improvement comprising liquid injection means in said by-pass conduit at the junction of said liquid by-pass conduit comprising an outer elongated cylindrical tube having a gas inlet tube on one end thereof and a gas outlet tube on the other end, an inner elongated cylindrical tube coaxially arranged relative to said outer tube, means projecting through said outer tube providing liquid access to said inner tube and fixed sized orifices in said inner tube spiralled therearound in heat exchange relation with the hot gas in said gas by-pass conduit wherein said orifices are so calibrated as to bring the liquid to a boil before said liquid is spray injected into said gas by-pass conduit whereby the spray injected liquid absorbs heat from the hot gas to effect complete vaporization of said injected liquid to prevent a slug of liquid from reaching the compressor.

5. In a refrigeration system having automatic capacity control means for vary-ing the capacity thereof including a compressor, condenser, receiver and evaporator hav- .7 ing the usual hot gas line from the outlet side of the compressor to the "condenser, a suctionwline from the in: let side of the compressor to the evaporator and a liquid line from the receiver to the, evaporator, a hot gasbypass conduit directly connecting the outlet and inlet sides,

of said compressor, a liquid by-pass conduit directly connectingfsaid' receiver and rsaid gas by-pass conduit, and means for regulating the flow of gaseous refrigerant aaenaeo throughzsaid gas by-pass conduit responsive to conditio'ns in the system indicative'of the load on the evaporator and pressure in the suction line; the improvement com prising liquidrinjection means in said gas by-pass con-' cluitat the junction of said liquid by-passconduit comprising an outer elongated cylindrical tube having a liquid access aperture therein, an inner elongated cylindrical tube coaxially arranged relative to said outer tube having a gas inlet tube on one 7 end thereof and a gas outlet tube on the other end and fixed sized orifices" 1 line from the receiver'to the evaporator, a hot gas bypass conduit directly connecting the outlet and inlet sides of said compressor, and means forv regulatng the flow of gaseous'refrigerant through said hotgas by-pass conduit responsive to pressure conditions in said suction line; the. improvement comprising means'fo'r automatically injecting spray droplets of liquid refrigerant in a spiral pattern into direct heat exchange contact With'the hot gaseousrefrigerant flowing through said hot gas by-pass conduit quantities or liquid refrigerant extracted from a location between said condenser and said evaporator in- -cluding mea'ns for regulating the quantity ofsthe introduced liquid refrigerant responsive to thermal conditions 7 of the suction line' gas returned to said compresin said inner tube spiralled therearoundinheat exchange 1- relation Withthe hot gas in said' gas by-pass conduit wherein: said ,orifices are so calibrated as fitorbring the liquid to a boil before saidlliquid is spray injectedinto said gas by-passconduit. whereby the sprayinjected sor to substantially that quantity required to maintain the return I gasfbelowcompressor damaging temperature and effect complete vaporization of the introduced liquid refrigerant, said means for 'automaticallyinject-ing spray droplets of liquid refrigerant comprising means forming achamberiof concentric members, one of said members 7 having sized orifices spiralled therearound.

liquid absorbsheat from'the hot gas toetfectcomplete compressor to,' the condenser, a suction line from the in-' let side of the compressor to the evaporator and a liquid 7 V ReferencesCited by'th eExaminer UNITED STATES PATENTS V OTHER REFERENCES ,Germanrprinted application No. 1,055,561, printed April 23, 1959. i

p PER IQIN, Primary Examiner,

ROBERT A; OLEARY, xaminer, 

1. IN A HAIR ORNAMENT, A FIRST PLATE MEMBER, A SECOND PLATE MEMBER LOCATED IN EDGE-TO-EDGE ABUTTING RELATION WITH RESPECT TO SAID FIRST PLATE MEMBER AND BEING NORMALLY IN SUBSTANTIALLY THE SAME PLANE THEREWITH, A COIL SPRING MEANS CONNECTING SAID MEMBERS AND SAID COIL SPRINGS, SAID COIL SPRING HAVING ITS LONGITUDINAL AXIS EXTENDING FROM ONE PLATE MEMBER TO THE OTHER IN OVERLYING AND GENERALLY PARALLEL RELATION WHEN SAID PLATE MEMBERS ARE IN THEIR NORMAL EDGE-TO-EDGE ABUTTING RELATION, THE ADJACENT CONVOLUTIONS OF SAID SPRING BEING LOCATED IN MUTUALLY ABUTING RELATION WHEN SAID SPRING IS IN THE NORMAL RELAXED POSITION THEREOF, SAID PLATE MEMBERS BEING MOVABLE RELATIVE TO EACH OTHER, THE ABUTTING EDGES DEFINING A PIVOT AXIS THEREFOR, SAID COIL SPRING HAVING MEANS INCLUDING EXPOSED ONES OF SAID CONVOLUTIONS WHEREBY, UPON MOVEMENT OF SAID PLATE MEMBERS CAUSING SAID COIL SPRING TO BE TENSIONED, THE ADJACENT CONVOLUTIONS THEREOF ARE SEPARATED TO DEFINE SPACES INTO WHICH STRANDS OF HAIR OF THE WEARER ARE INSERTED, SAID SPRING CAPTURING THE STRANDS OF HAIR BETWEEN THE ADJACENT CONVOLUTIONS WHEN THE PLATE MEMBERS ARE RELEASED FOR RETURN TO THEIR NORMAL POSITION. 